Prior to any sort of official announcement by Electronic Arts or developer DICE, it looks as though the open beta dates for Battlefield 2042 seem to have leaked. While there is a chance that the dates in question could be inaccurate, the manner in which they have leaked seems to tell us that there is quite a bit of legitimacy here and could give us a better idea of when we'll be able to try out the game before launch.
Found via Chinese video website Bilibili, it has been said that the Battlefield 2042 beta is set to kick off next week on October 6. The leak in question states that it will run until October 9, although this date may not be indicative of the beta's conclusion. Further details of how the beta itself will roll out weren't really given, nor was it specified if this span is one that would be open to all players. That being said, Electronic Arts does have an official Battlefield 2042 streaming page on Bilibili, so the fact that these dates appeared on said page seems to suggest that this leak is very much legitimate.
As mentioned, the one problem with this current date span for the Battlefield 2042 beta is that October 9 happens to be a Saturday. In all certainty, those at EA and DICE won't end the beta on a Saturday given that nearly every trial phase for a game of this type typically transpires through the weekend. As such, there's a chance that the October 6 through 9th dates could instead indicate that an early access phase of the beta could be available to certain groups. For instance, some publishers often give players who pre-ordered the game early access to the beta ahead of time as a way of saying thank you for being an early adopter. That could very well end up being the case here with Battlefield 2042 as well.
We'll have to wait until an official announcement from EA and DICE to know for certain if this leak is true, but in all likelihood, we should hear more on this matter in the very near future. Until then, you can continue to plan to see Battlefield 2042 as a whole release later this fall on November 19 for PlayStation 5, PlayStation 4, Xbox Series X, Xbox One, and PC.